S14 - Session O6 - De novo genome sequencing of Eremocitrus glauca and Murraya spp. as sources of resistance to citrus Huanglongbing

Authors: Concetta Licciardello *, Simone Scalabrin, Giusi D'Amante, Maria Patrizia Russo, Paola Caruso, Marco Caruso, Michele Vidotto, Mônica Neli Alves, Nelson A. Wulff, Davide Scaglione, Leandro Peña

Huanglongbing (HLB), also known as citrus greening, represents the most devastating disease for citriculture, as it is causing the death of millions of trees, heavily decreasing the production and causing an annual economic loss of hundreds of million $. All the worldwide citriculture is threatened because all commercial citrus species and varieties are susceptible to HLB. New curative and preventive measures are needed as well as identifying sources of durable and stable resistance to be used in breeding programs. Greening is associated to three species of Candidatus Liberibacter ( C L), transmitted by two psyllids, Diaphorina citri and Trioza erytreae . C L asiaticus (CLas) - D. citri is the most aggressive C Lnvector combination . T. erytreae has been already detected in Portugal and Spain. Unfortunately, once the vector has spread widely, bacterial dispersal may occur rapidly. Therefore, one of the most ambitious challenges consists in the characterization and use of sources of resistance in Citrus relatives. Eremocitrus glauca and several Microcitrus specieshave been described as full-resistant to CLas but the resistance genes were not identified yet. Among Murraya spp, M. paniculata is a transient host for C Las, M. koenigii is full resistant, while the behavior of M. ovatifoliolata is less clear. We present the de novo genome sequencing of E. glauca, M. paniculata and M. ovatifoliolata by using a combination of long-reads (Oxford Nanopore) and short-reads (Illumina) technologies. A genome of around 270 Mb was produced for E. glauca , 220 Mb for both Murraya species. Genomes were assembled in pseudomolecules; genes were predicted and annotated. These data will support further experiments aimed at identifying and characterizing genetic sources of resistance. They will be strategic for cisgenic or genomic editions approaches, to introduce the resistance in susceptible species, as well as to understand the inheritance of resistance in cross populations of E. glauca with Citrus species.